From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Sat, 30 Aug 2014 22:31:21 +0000 (-0400)
Subject: sd-dhcp6-client: properly calculate buffer size when parsing options
X-Git-Tag: v217~692
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=44481a8b537839cd9ffead4d261491641f5b5260

sd-dhcp6-client: properly calculate buffer size when parsing options

Also make pointer calculations more explicit so they are
easier to understand.
---

diff --git a/src/libsystemd-network/sd-dhcp6-client.c b/src/libsystemd-network/sd-dhcp6-client.c
index 342a23141..6860c6685 100644
--- a/src/libsystemd-network/sd-dhcp6-client.c
+++ b/src/libsystemd-network/sd-dhcp6-client.c
@@ -583,12 +583,15 @@ static int client_parse_message(sd_dhcp6_client *client,
                                 DHCP6Message *message, size_t len,
                                 sd_dhcp6_lease *lease) {
         int r;
-        uint8_t *optval, *option = (uint8_t *)(message + 1), *id = NULL;
+        uint8_t *optval, *option, *id = NULL;
         uint16_t optcode, status;
         size_t optlen, id_len;
         bool clientid = false;
         be32_t iaid_lease;
 
+        option = (uint8_t *)message + sizeof(DHCP6Message);
+        len -= sizeof(DHCP6Message);
+
         while ((r = dhcp6_option_parse(&option, &len, &optcode, &optlen,
                                        &optval)) >= 0) {
                 switch (optcode) {
diff --git a/src/libsystemd-network/test-dhcp6-client.c b/src/libsystemd-network/test-dhcp6-client.c
index 259db33bc..d102a796b 100644
--- a/src/libsystemd-network/test-dhcp6-client.c
+++ b/src/libsystemd-network/test-dhcp6-client.c
@@ -205,7 +205,7 @@ static uint8_t msg_reply[173] = {
 static int test_advertise_option(sd_event *e) {
         _cleanup_dhcp6_lease_free_ sd_dhcp6_lease *lease = NULL;
         DHCP6Message *advertise = (DHCP6Message *)msg_advertise;
-        uint8_t *optval, *opt = &msg_advertise[sizeof(DHCP6Message)];
+        uint8_t *optval, *opt = msg_advertise + sizeof(DHCP6Message);
         uint16_t optcode;
         size_t optlen, len = sizeof(msg_advertise) - sizeof(DHCP6Message);
         be32_t val;